This may be a transition model like my '64 Fender Reverb Unit, which, from what I've been told by some folks on Surf Guitar 101 forum, are fairly unique. When I bought my Reverb Unit from Carter's Vintage Guitars, they had identified it as a '62. After showing the Reverb Unit on the SG101 forum, far more experienced vintage Fender gear enthusiasts than I kindly pointed out that it was in fact a '64. Here's the link to that thread if anyone is interested: NFRUD - 1964 Fender Reverb Unit